improve DDC's type checks

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart

Index: pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart
index 14f89cf55ef8da5fe9efde43a77272f1f50dbff0..3762f8b4fc4a0eca9c7a1aeaf25153e4f34fb683 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart
@@ -21,34 +21,6 @@ void ignoreAllErrors(bool flag) {
   JS('', 'dart.__ignoreAllErrors = #', flag);
 }
 
-throwCastError(object, actual, type) {
-  var found = typeName(actual);
-  var expected = typeName(type);
-  if (JS('bool', 'dart.__trapRuntimeErrors')) JS('', 'debugger');
-  throw new CastErrorImplementation(object, found, expected);
-}
-
-throwTypeError(object, actual, type) {
-  var found = typeName(actual);
-  var expected = typeName(type);
-  if (JS('bool', 'dart.__trapRuntimeErrors')) JS('', 'debugger');
-  throw new TypeErrorImplementation(object, found, expected);
-}
-
-throwStrongModeCastError(object, actual, type) {
-  var found = typeName(actual);
-  var expected = typeName(type);
-  if (JS('bool', 'dart.__trapRuntimeErrors')) JS('', 'debugger');
-  throw new StrongModeCastError(object, found, expected);
-}
-
-throwStrongModeTypeError(object, actual, type) {
-  var found = typeName(actual);
-  var expected = typeName(type);
-  if (JS('bool', 'dart.__trapRuntimeErrors')) JS('', 'debugger');
-  throw new StrongModeTypeError(object, found, expected);
-}
-
 throwUnimplementedError(String message) {
   if (JS('bool', 'dart.__trapRuntimeErrors')) JS('', 'debugger');
   throw new UnimplementedError(message);